Production of dehydrogenation products from aliphatic hydrocarbons and halogenated hydrocarbons



Patented Oct. 14, 1941 PRODUCTION OF DEnrnnoGENArroN' rnonoors FROM ALrPnA'rro' HYDRO- CARBONS AND HALOGENATED mnmo- CARBONS Hans Baehr and Wilhelm Deiters, Leuna, Germany, assiznors, by mesne assignments, to Jason, Incorporated, a corporation of Louisiana No Drawing. Application May 4, 1938, Serial No. 205,976. In Germany May 5, 1937 9 Claims.

The present invention relates to a process for dehydrogenating aliphatic hydrocarbons of paraiilnic and olefinic character and/or their partially halogenated derivatives, containing from 3 to 8 carbon atoms.

A primary object of our invention is to use halogen, more particularly chlorine, for the dehydrogenation of the said compounds in the gaseous phase.

4 A further object is to prepare hydrocarbons poorer in hydrogen from hydrocarbons richer in hydrogen or fromhalogenated hydrocarbons capable ofconversion into hydrocarbons still richer in hydrogen under the reaction conditions than the end product desired A preferredobject of our invention is to prepare diolefinic hydrocarbons from mono-oleflnic and saturated hydrocarbons having the same number of carbon atoms.

It is well known that when saturated and unsaturated hydrocarbons react with chlorine, there may be various substitution reactions, or, in the case of unsaturated hydrocarbons, also addition reactions. Thus aliphatic hydrocarbons of the paraflin series may be reacted at elevated temperatures with halogen to form monoand polyhalogenated hydrocarbons having the same length of carbon atoms. Olefiriic hydrocarbons, when reacted with ha ogen at elevated temperatures, may form halogen substituted unsaturated hydrocarbons. In any of these cases the direct formation of dehydrogenation products by the elimination of. hydrogen without halogen substitution has hitherto not been observed.

We have obtained in the treatment of aliphatic hydrocarbons and their partially halogenated derivatives with halogen at elevated temperatures considerable amounts of dehydrogenation products in addition to halogenated products formed by substitution. We have. also found that by controlling the conditions we may increase the proportions of the dehydrogenation products.

Our process for the dehydrogenation of paraffinic and olefinic hydrocarbons having from 3 to 8 carbon atoms consists in thoroughly mixing the materials to be dehydrogenated with such an amount of halogen'as is necessary for the tanes, pentanes, hexanes and octanes and the corresponding olefines, such as butylenes, amylenes, di-isobutylene, and the partially halogenated derivatives, especially those obtained as byproducts in the preparation of the dehydrogenation products; The starting materials may be used in a pure state, either as individual saturated and unsaturated compounds or in a'dmixture with one another or with halogenated compounds. The source of the compounds used is immaterial. The hydrocarbons may be derived from mineral oil or from natural or coke oven gas or from the hydrogenation of carbonaceous materials -or from pyrolytic and cracking processes. Furthermore such mixtures may be used in the form of hydrocarbon fractions consisting of hydrocarbons containing the same number of carbon atoms, as a butane-butylene cut, pentaneamylerie out, etc. The oleflnes. may as'well be obtained by the dehydration of alcohols. Chlorine is the preferred halogen to be used in our flame propagationjas for example at a speed of formation of hydrogen halide with the hydrogen to be split off, causing the mixture "to react at.

elevated temperature, in the presence or absence of catalysts, cooling the reaction mixture as rapidly as possible, and isolating a fraction rich in dehydrogenation products.

Suitable materials for/the process are normal 100 meters or more per second. After adding the whole of the desired amount of chlorine, the resulting mixture is preferably led at the same high speed through tubes with inserted twisting bodies or rifling and thereby whirled through each other for the purpose'of especially thorough mixing. A specially, thorough mixing mayalso be obtained for example in a tube in which the necessary irregularities in the gas flow are produced by alternate restrictions and widenings compounds, especially partially chlorinated hyand branched chain parafilns as forexample bu drocarbonshaving the same number of carbon atoms and to saturate them therewith correspending to the vapor pressure.

One or more of the reactants may also be heated before or during the mixing; for example the hydrocarbons or chlorinated hydrocarbons may alone be heated and reacted when well mixed with the unheated chlorine, or on the other hand the chlorine may be heated, mixed with the nonpreheated other initial material and reacted. Finally all the reactants may be heated before or during the mixing. The mixing of the gases may also take place in the reaction chamber itself, for example by blowing the preheated reactants into the reaction chamber through nozzles constructed like bumers.. It is also possible to introduce the heated initial mixture, separated into a plurality of partial streams, at different parts of the reaction vessel. Inert gases, as for example nitrogen, water vapor or carbon dioxide may also be added to the initial material or the mixture; In all cases, the mixing shouldbe as thorough as possible.

The heating of the initial materials or their mixtures used according to thisinven'tion may be effected externally, as for example by leading them through hot tubes, or internally, as for example byleading in heated inert gases, as for example nitrogen or steam, such as are formed by burning hydrogen with oxygen-Electrical internal heating or eddy current heating may also be used. It is especially suitableto use the heat Y of reaction for preheating one or more of the reactants. The preheating is generally speaking carried to temperaturesbetween about 100 and 500 C.

The mixture prepared in one of the said wafys is supplied to the reaction chamber either cold or hot and led at a. high velocity, so that it enters the place, at which the reaction properis liberated by thermal actionin empty vessels or by contact with heated filling bodies or catalysts; in excess of the speed of flame propagation. The initiation of'the reaction is preferably effected by leading the gas mixture against a glowing body or against a fiame. In-order to avoid undesirable side-reactions, it may be preferable to ignite-with a chlorine-detonating gas flame. The

glowing bodymay be brought to the necessary 7 temperature by direct-heating or by an electric current. An inbuilt spark gap may also be usedfor ignition. Though catalysts or filler bodies I may entirely be dispensed with, such substances may be used, especially when dehydrogenating mixtures containing chlorinated hydrocarbons.

Among suitable catalysts there may be mentloned graphite, coke, pumice stone, silica gel, silicon carbide, activated oxides, ceramic masses of acida and basic nature, and also other known halogenationcatalysts, such as the halides of copper, lead, nickel, tin, zinc, cadmium, bismuth,

calcium,

aluminium, magesium, manganese, thorium, potassium, silicon or mixtures of the same, The said metal halides-may also be applied to the said carrier substances.

\ more and more preponderant.

with the amount 'ofchlorine used, and also depends on the speed of flow at which the reactants are led through the reaction vessel. In general, the reaction temperature lies between 300 and 800 0., more particularly between 400 and 650 C. If the temperature is low, there is only a small proportion of dehydrogenation products formed, but pyrolysis and splitting of the carbon chain is completely avoided. If the temperature is high it becomes increasingly difficult to suppress the formation of compounds having less carbon atoms than the material to be dehydrogenated.

As already stated, the suitable reaction temperature also depends on the amount ofchicrin'e used. The amount of chlorine to be used, in turn, depends on the amount of hydrogen to be split off. For example in the conversion of a saturated hydrocarbon into an olefine, the proportion of the latter to chlorine is selected at about 1:1. ,In the preparation of diolefines from saturated hydrocarbons, the ratio of hydrocarbons to chlorine of about 1:2 is chosen. If mixtures of olefines and .dioleflnes are desired, ap-

chlorine being used for chlorination. On the other hand, if the amount of chlorine is too high, the formation of decomposition products such as vinyl chloride, methane and ethane, becomes Within the above defined limits the reaction may be carried out depending on the nature of the products desired. When producing butadiene according to our invention, for example butane may be first reacted with less than the equimolecular proportion of chlorine. After having cooled off the reaction products and having removed the hydrogen chloride, the butylene formed may be separated ofi by causing it to react with chlorine to produce butylene chloride. This may be effected by treating the butylene, eithenin the pure state or in the presence of the other ingredients contained in the reaction products, at temperatures between about 30 and +l00 C. with the necessary amount of chlorine.

- The butylene chloride may then be converted The courseof the reaction may be influenced,

to a great extent by using different pressures, as

'well as by using protecting gases or by varying the speed of fiow. The reaction is preferably carried out in vessels in which the ratio of the surface to'volume has been strongly displaced in favor 8f the surface. The reaction is especially favored by the graphite formed in the reaction vessel which is deposited as acoating on the walls andwhlch renders the use of fillers un-' necessary.

The optimum temperature for the.dehydi-ogenation varies with different hydrocarbons and into butadiene by splitting off two molecules of hydrogen chloride according to one of .the usual methods or preferably according to the process of our co-pending application Ser. No. 164,502, filed September 9, 1937.

Butane may also be reactedjwithv an excess of chlorine, and butadiene be recovered from the reaction products for example by treating them with salts of heavy metals of the first and second group of the periodic system. .The-remaining mixture may either be recycled without further purification or be fractionated, the butylene being converted into butadiene'by adding on orine and splitting off hydrogen chloride.

The reaction may also be carried out by sub- "plying the amount of chlorine necessary for the formation of hydrogen chloride with the hy-' drogen to be split off to the materials to be dehydrogenated through suitable distributors and mixing devices in two or more stages which are separated from each other by reaction zones.

This renders it possible to guide the process also on a technical scale by dosing of the amounts of chlorine and by regulating the temperatures before and in the single reaction stages. Each mixing, should be carried out with the aid or eflicient devices, as for example porous bodies, mixing nozzles or rifled tubes, so that the chlorine is dispersed as completely as possible within the shortest possible time. .By adding the chlo rine in stages, thereaction is subdivided and its whole course rendered milder. The temperatures in the diiferent stages may be different; it is preferable to increase the reaction temperature from stage to stage in the direction of the passage of the gas.

- hydrogen and, if desired, ethylene formed and purified by distillation. The separation of the diolefines from the olefines may also be effected in known manner, as for example by treatment with salts of heavy metals of the first and second groups of the periodic system.

The nature of this invention is further illustrated in the following examples, but the invention is not restricted to these examples.

This offers the advantage that the temperatures can be accurately maintained be-' causeall intermediate stages of the chlorination cooling or heating. Directly after leaving the reaction chamber, the reaction mixture should be cooled as rapidly as possible. This may be effected by direct or indirect cooling. For example water or other liquids, such as lye or oil, maybe sprayed in. The chlorine compounds obtained in the process as by-products are especially suitable for quenchg ing the gaseous reaction mixture. (At the same time hydrogen chloride is split ofl therefrom' thereby and an additional formation of olefines and diolefines is thus obtained. r

' The reaction mixture obtained, which contain a preponderating amount of oleflnes or-diolefines ,and hydrogen chlorideand chlorinated hydro- I carbons of saturated and unsaturated nature in addition to small amounts of cleavage products,v may be freed by cooling from the greater art of the chlorinated hydrocarbons obtained as byproducts and then from the hydrogen chloride formed by washing or by distillation. Water or lye or diluted hydrochloric acid may be, used for thewashing; The last traces of hydrogen chloridemay be bound in known manner with the 4 aid of so id alkalies.

As already mentioned, the chlorinated-hydro carbons obtained as by-products, which have the same number of carbon atoms as the hydrocar- Ezample 1 60 liters per hour of normal butane and 120 liters per hour of chlorine are led together after drying both gases and thoroughly mixed in a narrow bulb tube centimeters long. The mixture is blown through a quartz tube 2 millimeters wide against a frontal plate heated externally to bright red heat and arranged ina quartz tube 15 millimeters wide. The resulting reaction mixture is led through a lateral attachment to the quartz tube into a cooling chamber and then through lye receivers' and-thus freed from hydrogen chloride formed. It is then split up into a condensable and an unconden'sable, fraction in a vessel cooled with carbon dioxide snow.

In this way 63 liters-of condensable hydrocarbons are obtained from 116 liters of normal butane.

These contain in all 94 per cent of olefines and diolefines of which 68 per cent is butadiene. There arealso obtained-148 cubic centimeters of liquid chlorination products boiling for the most part between and 70 and 110 and 120 C, and consisting of monoand di-chlorbutane. The gas not condensed inthe vessel cooled'with carbon dioxide snow amounts 'to 20 liters. It contains 50 per cent ofethylene, 5 per cent of hydrogen .and 18 per cent of methane. Q

v ".The mixture consisting of 'butylene and butadiene is led through an acid solution .of cuprous' chloride kept at ordinary temperature. This solution is then heated to 60 C. whereby a gas containing about 96 percent of butadiene is obtained. It may be polymerized 'in known manner.

The butylene, which has not been absorbed by the cuprous chloride solution, is admixed .with

an equi molecular amount of chlorine and led through a tube cooled with cold water. Dichlorbutane, having a boiling point of 117 C. is'thus obtained. It is heated to about 300 C. and led with high velocity over a rod from silicon carbide electrically heated to bright red heat. The rebons used, may also in turn be converted into f diolefine is obtainable therefrom directly by splitting ofi' hydrogen chloride, they are used for quenching the reaction mixture and-thereby converted into oleflnes or diolefines. I f, however, the introduction of further chlorine thereinto is necessary in order to obtain the desired unsaturated hydrocarbons, they are led, after admixing the necessary amount of chlorine, together with the mixture of hydrocarbon and chlorine into the reaction chamber again.

The reaction mixture freed from hydrogen' chloride and the greater part of the chlorinated hydrocarbons formed and, if desired, after removal of the last traces of chlorine compounds, may be liquefied by cooling and compression and freed from small amounts-of methane; acetylene,

If the desired olefine or suiting mixture contains butadiene in a yield of per cent.

- Example 2 I 1 cubic 'meter perhour of normal butane is led through monochlorbutane having a boiling point of from 60 to 70 CI, obtained as described .in Example '1, heated to'50 c. and then mixedquartz tube 6 millimeters in internal width and blown against a frontal wall heated to bright red heatby direct heating with a chlo'rine-detonating I gas flame which is situated in a quartz tube of 42 millimeters internal width. Directly behind the reaction zone, 200 cubic centimeters per hour of finely dispersed dichlorbutane having aboiling point of from to 0., obtained as described in Example 1, are sprayed in and the reby volume o! total oieflnes and 42, per cent of in addition to a little acetylene, methane and *tin, lead, bismuth, barium, cadmium and the meters and a length of 150 millimeters ,and which action .product is further cooled by cooling, freed from hydrogen chloride by washing with lye and then condensed by cooling with carbon dioxide snow.

From 1 cubic meter of butane and 1 literof monoand di-chlorbutane there are obtained: 665 liters of condensable gases with 91.4 per cent by volume of total oleilnes and 64.1 per cent of butadiene, 200 liters of a gas containing, in addition to a few per cent of chlorine compounds a little methane, acetylene and hydrogen, about 60 per cent by volume of ethylene, and 1.5 liters of liquid products which mainly boil at from 60\ to 70 and from 110 to 130 C. and which consist of monoand di-chlorbutane.

Example 3 From 50 liters of normal butane there are obtained: 33 liters of 'condensatewith 84 per cent butadiene by volume, 62 cubic centimeters of liquid product mainly boiling between 60 and 70 C. and 12 liters of gas containing mainly ethylene hydrogen.

The following catalysts give similar results under the same conditions; active carbon, silicon tetrachloride p on silica gel; the chlorides of aluminium, nickel, manganese, magnesium, zinc,

oxychloride bismuth, all on active carbon as carrier mass. Example 4.

. liters per hour of isobutane are mixed with 50 liters per hour ofchlorine in the manner de- 1, scribed in Example 1- and blown against a brightglowing plate. After quenching, removing the hydrogen chloride and cooling with carbon dioxide snow, there are obtained 30 liters of condensate with 83 per cent by volume of total oleflnes and 6'7 per cent by volume of isobutylene. Moreover there are obtained 85 cubic centimeters of liquid product mainly boiling between 50 and 70 C. and 11 liters of gas containing62 per cent of olefines in addition to a little acetylene, methane and hydrogen.

' Example 5 4 110 liters hour of normal butylene and 110 liters of chldiine are mixed at a great speed of flow in a mixing nozzle at ordinary temperature and led through a reaction tube consisting of silicon carbide "which has a diameterpf .5 milli- 05 is filled with small pieces oi. silicon carbide. So muchheat is developed by the initiated reaction that the reaction tube is kept at a weak red heat. By cooling the reaction. gases to about 0 C.'there are obtained cubic centimeters of an oil and, by .cooling'in a carbon dioxide snow bath, a con,- densate the, amount or which iri the vaporized state is '71 liters. There are also. obtained .14

liters of final gas which is not liquefied by cooling withthecarbon dioxidesnow.

- jects a second, narrower chamotte tube.

The oil obtained at 0 C. has a specific gravity of 0.98. It boils to the extent of from to per cent between 60? and 80C. and has an iodine value of 154. Accordingly it consists of monochlorhydrocarbons with 4 carbon atoms and to v the extent of from about 55 to 60per cent of unsaturated monochlorhydrocarbons. The condensate obtained by cooling in the carbon dioxide snow bath consists oi! 68 per cent of butadiene,

l per cent of unsaturated chloro-hydrocarbons,

in particular vinyl chloride, 21 per cent of unconverted butylene and 4 per cent of residual gas. There are thus obtained a yield of 48 per cent of butadiene, calculated on the initial material, and about 57.5 per cent of butadiene, calculated on the butylene converted.

- The monochlor'rhydrocarbons contained in the separated oil may be returned in circulation together with dichlorbutane and thus converted into butadiene.

' Emampleo For the reaction, avessel is used with consists of an empty chamotte tube into which proinner tube is so arranged that the reaction gases led into the same must flow back through the outer tube.

Through a container with iso-pentane there is led at about 20 C. 0.5 cubic meter of nitrogen per hour, whereby- 7.5 kilograms=2.4' cubic meters of iso-pentane are vaporized per hour.

This mixture of pentane and nitrogen is then thoroughly mixed with 3.6 cubic meters oi chlorine. The proportion of pentane to chlorine thus amounts to 1:15 and therefore corresponds to the composition calculated for the preparation of a mixture of,amylene and isoprene. The initial mixture is heated to initiate the reaction to a temperature of about 550 C. and led through the inner tube of the reaction vessel.

The reaction takes place with strong evolution of heat in the outer chamber of the reaction vessel, the heat evolved being given up to the inner tube and serving therefor heating the continuously flowing mixture of iso-pentane, nitrogen and chlorine. The reaction mixture is rapidly cooled to 30- C. and the hydrogen chlo-- fide formed washed out by treatment with water. 38y this cooling there are obtained at the same time 1.5 kilograms of a liquid which consists of saturated and unsaturated chloro-r hydrocarbons, in particular chlorpentane. The gas mixture is further cooled to 20 below zero 0., whereby 6.2 kilograms of a liquid are obtained which is vaporized and split up into (ii oleflnes and mono-olefines with the aid oi. an acid cuprous salt solution. In this way there are obtained 3.0'kilograms of diolefines, in particular isoprene, 2.2; kilograms of iso-amylene and 0.5 kilogram of unconverted iso-pentane. There 'is alsoobtained per hour 1 cubic meter of final gasconsisting of 50 per cent of nitrogen, 40 per cent of oleflnes, in" particular butylene,

propylene and ethylene, and about 10 per cent of hydrogen and methane.

\ The iso-amylene and the chlorpentane may be returned in circulation for further splitting up to dioleflnes.

Example 7 10 cubic meters per hour .of normal butane,

are mixed in. a nozzle-shaped burner with 15 cubic meters per hour of chlorine which has been preheated in a tubular spiral to 400 C. This mixture isled at a speed of flow of 20 The- . ing the butyelene,

perature of about 600C. leaving" the reaction chamber are quenched with water, the hydrogen chloride formed thus being separated at the same time. There are also thus obtained 3.2 liters oi liquid chloro-hydrocarbons the iodine value Example 9- As a reaction vessel, use is made of a stonemeters of normalbutylene per hour are led at of which is about 70 and which consist mainly of chlorbutanes and chlorbutylenes. The gas mixture freed from hydrogen chloride is then cooled under a pressure of atmospheres to 0., whereby the greater part is liquefied; there are also obtained about 1.5 cubic meters of final gas consisting to the extent of about 60 per cent of unsaturated hydrocarbons, in particular ethylene, and volatile chloro hydrocarbons; By

vaporizing the mixture liquefied under pressure which consists of 94 per cent of unsaturated compounds, namely 45 per cent of butadiene, 12 per ent of unsaturated chloro-hydrocarbons, in

particular vinyl chloride, and 37 per cent of butylene, and about 6 per cent of unconverted butane. Moreover there remains a non-vaporized portion of 0.5 liter consisting of chlorbutanes and chlorbutylenes. The yield of butadiene amounts to 36.9 per cent and that of normal butylene to 30.3 per cent, calculated on the normal butane introduced, by a single passage. The normal butyelene and the chloro-hydrocarbons may, if desired, be supplied again to the reaction, whereby the total yield of butadiene may be considerably increased. v

Example 8 10 cubic meters of butylene heated to 300 C.

are thoroughly mixed with 10 cubic meters of chlorine heated to 350 C.-'and the mixture is led through an empty tube at a speed of flowof 40 meters per second. For the reaction-a vessel is used consisting of an empty chamotte tube into which projects a second, narrower chamotte tube. The inner tube is arranged so that the reaction gases led therethrough must flow back through the outer tube. In the outer of the chambers formed by the two concentric tubes, the reaction" between the butylene and the chlorine takes place, temperatures of from about 650 to 700 C. being attained. A part of the heat of reaction is given up to the inner tube, whereby the initial gas'led through the innertube is preheated. The residual heat of reaction is carried away bythe reaction gas and removed by spraying water into the same, whereby the hydrogen chloride ,formed is removed taining- 70 per cent of olefines, mainly butylene.

If the condensate obtained by cooling to 80 below zero C. be vaporized at room tempera-- ture, there are obtained. 9.1 cubic meters of a gas mixture consisting of 97 per cent of monoand di-olefines of which about 82 per cent is butadiene. There also remains a non-vaporized portion of about 1.2 liters, consisting mainly oi chlorbutylenes. The butadiene is separated by distillation from the butylene and the latter is returned in circulation. The yield of butadiene is 74.6 per cent by a single passage; By retum even higher.

the yield of butadiene becomes there are obtained 8.2 cubic meters of a gas I a speed" of flow of 10 meters'per second (calculated cold) throughthe stoneware tube which is' kept at a temperature of about 550 C. by returning the hot reaction gases along the outer wail. 6 cubic meters -'per hour of chlorine are mixed with the hydrocarbon mixture through the porous stoneware candle arranged in the interior. The gas mixture leaving the reaction chamber is immediately quenched by coolin with water, freed from hydrogen chloride by washing with lye and iractionally condensed by leading into a cooled vessel. By reaction for one hour, the following products are obtained:

1.8 liters of liquid olefinic chloro-hydrocarbons having a boiling point mainly between 70 and I Example 10 A porous stoneware candle is arranged concentrically withina stoneware tube which is heated to 150 C. In this apparatus, 5 cubic meters per hour of normal butane are mixed at a speed of fiow of 10 meters per second (measured cold)v with 5 cubic meters per hour of chlorine which is introduced through the porous candle. Reaction takes place between the butane yields butylene'and hydrogen chloride as well as chlorbutanes. The reaction gas of the first stage is then mixedin a chamber heated to 550 C. with a further 5 cubic metersper hour of chlorine which is introduced through a second concentrically arranged mixing candle. The item perature of the second chamber maintains itself without additional heating after a shortlinitiation ti e.' The reaction gas leaving .this chamber is quenched by indirect water-cooling, freed from hydrogen chloride by washing with lye and split up'into its single components by leading into a cooling vessel.

In this way the following substances-are ob- 6.8 cubic meters of gas condensable in a bath of carbon dioxide snow containing 70 per cent of total'olefines of which 54 per cent is buta'diene; 0.9 cubic meter of final gas containing. 62 per ucts boi ng at from "70 to 80 and from to C. onsisting mainly of olefinic .chloro-hydrocarbons.

What we claim is: Y

1. The process of dehydrogenating butane which consists in causing a mixture ofbutane with chlorine, containing at least 0.3 and at most about 2.2 molecular proportions of chlorine for one molecularpro'portion of butane, to react in the gas phase at temperatures between 300 and 800C the time of heating and the tempera-.

ture being so chosen as to avoid substantial formation of compounds havingless carbon atoms than .the hydrocarbon to be dehydrogenated, quenching the gaseous reaction mixtureto about and the chlorine; this proceeds at 500 C. and

tained from 10 cubic meters of normal butane:

cent of ethylene; and 9.4 liters of liquid prodordinary temperature by contacting it with par tially chlorinated aliphatic hydrocarbons containing 4 carbon atoms, removing the hydrogen chloride by contacting the gaseous reaction mixture with a solvent for hydrogen chloride,and separating the unsaturated hydrocarbons obtained from co-present material. I

2. The process of dehydrogenating butane which consists in causing a mixture of butane with at" most 1 and at least 0.3 molecular proportion of chlorine to react at temperatures be- I tween 300 and 800 C., the time of heating and the temperature being so'chosen as to avoid substantial formation of compounds having less carbon atoms than the hydrocarbon to be dehy-. drogenated, cooling off the reaction mixture sub-- stantially below reaction temperature, removing the hydrogen chloride by contacting thereaction mixture with a solvent: for hydrogen chlotiori of chlorine; to react at temperatures between 3009 and 800 C.,- the time of heating and the temperature being so chosen as to avoid substantial formation of compounds having less car-.

bon atoms than the hydrocarbon to be dehydrogen-ated, cooling oif the reaction mixture sub- 1 stantially below reaction temperature, removing the hydrogenjchloride by contacting the reaction mixturewith 'a solvent for hydrogen chloride,

treating the remaining material with chlorine at temperatures below 100' C., fractionating' the rej action mixture formed to obtain therefrom aj fraction rich in butylene chloride, contactingthis 40 7., The process of dehydrogenating partially fraction with a glowing electrically heated body andseparating butadiene from the copresent; f

4. The process of dehydrogenating compounds of the class consisting of aliphatic hydrocarbons of the paramn and-mono oleflne series/containing 3-5 carbon atoms and their partially halo genated derivatives which consists in causing a mixture of the material tobe dehydrogenated and chlorine, containing at least 0.8 and at m'ost 2.2 molecular proportions of chlorine for one molecular proportion of the material to be dehydr'ogenated'to react inthe gas phase at .temperatures. between 300 and 800 C.,.the time of heating and the temperature being so chosen :as to' avoid substantial formation of compounds containing .less carbon atoms than the compound to be dehydrogenated, quenching the gaseous reaction mixture to about ordinary temperature by contacting it with partially chlorinated aliphatic' hydrocarbons containing substantially the same numberof carbon atoms as the material to be dehydrogenated, removing the hydrogen chloride bycontactlng the gaseous reaction mixture with a solvent for hydrogen chloride and separating. the unsaturated hydrocarbons obtained from co-present material:

sh-rue process of. dehydrogenating compo nd, of the class consisting of aliphatic hydrocarbons l of the and mono-olefine series containing 3-5 carbon atoms and their partially halo- 1 genated derivatives which consists in causing a mixture of material to be dehydrogenated and chlorine, containing at least 0.3 and at most 2.2 molecular propo ons ofchlorine for one molecuiar'proportion of the; materialto ,be dehydroaasaios 5 taining less carbon atoms than the compound to .be dehydrogenated, cooling of! the reaction mixture substantially below reaction temperature, removing the hydrogen chloride formed by contacting the reaction mixture with a solvent for hydrogen chloride, treating the remaining material with-chlorine at temperatures below 100' C. and fractionating the reaction mixture formed to obtain therefrom'a fraction rich in oleflne chlorides.

l5 6. The process of dehydrogenating compounds of the class consisting of aliphatic hydrocarbons of the paramn and mono-oleflne series containing 3-5 carbon atoms and their partially halogenated derivatives which consists in causing a mixture '20 of material to be dehydrogenated and chlorine,

t 0.3 and at most 2.2 molecontaining atleas cular proportions of chlorineioronermolecular proportion of the 'material to be dehydrogenated. to react in the gas phase at temperaturesbow 2s tween 300 and 800 0., the time of heating and.

the temperature being so chosen as-to avoid 'substantial formation of compounds containing less carbon atoms-than the compound to be dehydrogenated, cooling of! the reaction mixture substantially below reaction temperature, removing the hydrogen chloride formed by contacting the reaction mixture with a solvent for hydrogen chloride, treating the remaining material with chlorine at temperatures below 100 C. and fractionating the reaction mixture formed to obtain ,halogenated aliphatic hydrocarbons containing 3-5 carbon atoms in the molecule which consists; in causing a mixture of thematerial to be de--' hydrogenated and chlorine, containing at least 1 450.3 and at most 2.2 molecular proportions ofv chlorine for one molecular proportionbf the ma-' 'terial to be dehydrogenated, to react in the gas phase at temperatures between 300 and 800 0.,

the time of heating and the temperaturebeing so. chosen as to avoid-substantial formation of compounds containing less carbon atoms than the compound to be dehydrogenated, quenching the gaseous reaction mixture to about'ordinarytemperature by contacting iiswith partially chlorinated aliphatic hydrocarbons containing substantially the same number. of carbon atoms as the material to be dehydrogenated, removing the hydrogen chloride by contacting the gaseous reaction mixture with a solvent for hydrogen chlo- 0 ride and separating ,theyunsaturated hydrocarbons' obtained from co-present material.

8. The process of dehylirogenatlng partially halogenated aliphatic hydrocarbons containing 'genated and-chlorine,;containing. at least 0.3 and at most-2.2 molecularproportions of chlorine for 'one molecular proportion of the material to be dehydrogenated, to react in the gas phase at temperatures between 300 and 800 C., the time of heating and the temperature being so chosen as to avoid substantial formation of compounds containing'less carbon atoms than the compou'nd to be dehydrogenated, cooling offthe reaction mixturesubstantially below. reactiontemperature, removing'the hydrogen chloride formed by contacting the reaction mixture with a solvent for hydrogen chloride, treating the remaining material with chlorine at temperatures below 100 C. and iractionating the reaction mixture formed to obtain therefrom a fraction rich in oleflne chlorides. v

9. The process of dehydrogenating partially halogenated aliphatic hydrocarbons containing 3-5 carbonatoms in the molecule whichconsists in causing a mixture of material to be dehydrogenated and chlorine, containing at least 0.3 and at most 2.2 molecular proportions of chlorine for one molecular proportion 01 the material to be dehydrogenated, to react in the gas phase at temperatures between 300 and 800' 0.. the time 

